In a process for preparing a semiconductor, forming a resist pattern on a wafer is now put into practice by using, for example, an apparatus shown in FIG. 8. In FIG. 8. "11" denotes a wafer; "12", a chuck for holding a wafer by absorption; "13", a shaft of a chuck; "14", a motor for rotating a shaft of a chuck; "15", a supporting plate and "16", a connecting part of an apparatus. As to the apparatus shown in FIG. 8, refer to microfilmed Japanese Utility Model Registration Application No. 61-135016 (1986) (Utility Model Kokai Publication JP-U-A-63-43427 (1988)), particularly its conventional art (FIG. 2).
At the outset, a resist is coated on a wafer and then exposed with an exposing apparatus. The resultant wafer 11 is held on a wafer chuck 12 and then rotated at a most appropriate number of rotation for equalizing the dimension of a pattern developed on the surface of the wafer without causing defects upon developing, and a developer is dropped by applying a spraying method or the like. After dropping, a paddle state of the developer cast up on the wafer to have a liquid thickness of about 2 mm is formed in order to progress developing without fault by maintaining the developer cast up on the wafer for a predetermined time, e.g., for about 60 seconds. Subsequently, the developer is splashed away from the wafer by high speed rotation followed by washing away with pure water and then the wafer is subjected to be dried while rotating.
Alternative to the rotary chuck with a stationary, straight axis of rotation, JP-U-A-63-43427, proposed a method wherein the chuck is rotated at a low speed while tiltedly swinging its rotational axis for distributing the developer and proceeding the developing.